The demand of acquiring large amounts of a specific segment of DNA efficiently for different purposes is booming in recent years. Among the entire existing DNA sequencing techniques, Polymerase Chain Reactions (PCR) is one of the most economical and straightforward techniques amplifying billion copies of targeted DNA segments in short period of time. The applications of PCR technique are broadly adopted, such as selective DNA isolation for genetic identification, forensic analysis for analyzing ancient DNA in archeology, medical applications for genetic testing and tissue typing, fast and specific diagnosis of infectious diseases for hospitals and research institutes, inspection of environmental hazards for food safety, genetic fingerprint for investigating criminals, and so on. For PCR technique, only small amount of DNA samples are required from blood or tissues. By utilizing fluorescent dye into the nucleic acids solutions, the amplified DNA segments could be detected through the help of fluorescent molecules.
To simultaneously detect and analyze the presence of targeted nucleic acids in a batch of biological samples, fluorescent dyes detection technique is usually applied. After the light source at specific wavelength illuminates on the targeted nucleic acids, the DNA-binding dyes or fluorescein-binding probes of the nucleic acids will react and enable fluorescent signals to be emitted. The fluorescent signal is an indication of the existence of the targeted nucleic acids. This technique has been employed for the novel PCR technique, which is called real time quantitative PCR or qPCR. qPCR is the early-phase PCR detection with higher sensitivity and better precision than the conventional PCR technique which is an end-point PCR detection. An optical device is essential to detect the fluorescent light emitted from the specific nucleic acids segments for qPCR technique. The optical device has to provide a light source to excite fluorescent probes at their specific wavelengths, and in the meanwhile, it detects the fluorescent signals emitted from the probes.
The fluorescent detection systems have been well developed in many fields, such as the application of fluorescence spectroscopy and fluorescence microscopy. An array of single color light source with a set of filters and optical components could easily apply on particular fluorescent probe. However, the difficulties of developing a fluorescent detection device for portable qPCR system have not been solved in the market because of its cost and size with high signal-to-noise ratio (SNR).
In light with the requirements and the issues addressed above, there is a need of providing an improved fluorescence detection device with high signal-to-noise ratio for qPCR application.